In the fields of refrigeration and air conditioning, energy saving aspects and efficiency are highly desired, and thus related systems require that evaporators and condensers for such systems have improved properties. In order to improve the properties of both the evaporator and the condenser, an enhancement heat transfer pipe with a higher heat transfer property is needed.
In horizontal shell pipe type condensers, refrigeration medium outside of the pipe is condensed so as to transfer heat by phase change, and coolant, such as water, flows through the pipe so as to transfer heat. Since the refrigeration medium outside of the pipe is cooled and condensed to form a liquid film outside of the outer wall of the pipe, the heat resistance at the refrigeration medium side is greater. Accordingly, the temperature difference loss leads to a decrease of the refrigeration efficiency, which affects the heat transfer property of the heat transfer pipe.
Generally, in order to enhance the heat transfer of the condensation side through phase change, fins can be formed on the outer surface of the heat transfer pipe by a mechanical machine, and a tooth crown is knurled to form a gap so as to form a zigzag. The primary function of this design is to enhance the heat transfer surface area, and the zigzag is used to reduce the thickness of the liquid film. Additionally, since the fins have a different radius of curvature in different positions, cooling liquid flows downward and is discharged collectively through a fin channel between the fins. Accordingly, the enhancement of the effect of heat transfer can be achieved.
Even though such mechanical processes can improve the heat transfer of the condensation side, these processes still do not meet the requirements of the refrigeration equipment to the heat transfer property of the condenser. Therefore, a need exists for the enhancement of heat transfer technology so to improve the heat transfer property of the condensation heat transfer pipe.